How Do People Get Hepatitis B?

Who Is at Risk for Hepatitis B?

In the United States, the most common way people get infected with HBV is through unprotected sex with someone who has the disease. People who share needles also are at risk of becoming infected because it's likely that the needles they use will not have been sterilized.

What Is Chronic Hepatitis B?

Doctors refer to hepatitis B infections as either acute or chronic:

An acute HBV infection is a short-term illness that clears within 6 months of when a person is exposed to the virus.

A person who still has HBV after 6 months is said to have a chronic hepatitis B infection. This is a long-term illness, meaning the virus stays in the body and causes lifelong illness. An estimated 850,000 to more than 2 million people in the U.S. have chronic HBV.

The younger someone is when infected, the greater the chances for chronic hepatitis B. About 90% of babies with HBV will develop a chronic infection. That risk drops to 6%–10% when someone over 5 years old is infected. Because of this, the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) recommend that all babies get the first dose of the hepatitis B vaccine within 12–24 hours of birth. (They'll get two more doses later, at 1–2 months of age and at 6–18 months of age.)

What Are the Signs & Symptoms of HBV Infection?

HBV can cause a wide range of symptoms, from a mild illness and general feeling of being unwell to more serious chronic liver disease that can lead to liver cancer. Someone with hepatitis B may have symptoms similar to those caused by other viral infections, like the flu. The person might:

HBV also can cause darker than usual urine (pee), jaundice (when the skin and whites of the eyes look yellow), and abdominal (belly) pain.

Someone who has been exposed to hepatitis B may start to have symptoms from 1 to 6 months later. Symptoms can last for weeks to months.

In some people, hepatitis B causes few or no symptoms. But even someone who doesn't have any symptoms can still spread the disease to others.

What Problems Can Hepatitis B Cause?

Hepatitis B (also called serum hepatitis) is a serious infection. It can lead to cirrhosis (permanent scarring) of the liver, liver failure, or liver cancer, which can cause severe illness and even death.

If a pregnant woman has the hepatitis B virus, her baby has a very high chance of having it unless the baby gets a special immune injection and the first dose of hepatitis B vaccine at birth.

Sometimes, HBV doesn't cause symptoms until a person has had the infection for a while. At that stage, the person already might have more serious complications, such as liver damage.

How Is Hepatitis B Diagnosed?

Someone with symptoms of hepatitis B or who might have been exposed to the virus through sex or drug use should see a doctor right away for a blood test. The blood test also can tell whether someone has an acute infection or a chronic infection.

How Is Hepatitis B Treated?

There's no cure for HBV. Doctors will advise someone with a hepatitis B infection on how to manage symptoms — like getting plenty of rest or drinking fluids. A person who is too sick to eat or drink will need treatment in a hospital.

In most cases, older kids and teens who get hepatitis B recover and may develop a natural immunity to future hepatitis B infections. Most feel better within 6 months. Health care providers will keep a close eye on patients who develop chronic hepatitis B.

What Happens After a Hepatitis B Infection?

Some people carry the virus in their bodies and are contagious for the rest of their lives. They should not drink alcohol, and should check with their doctor before taking any medicines (prescription, over the counter, or supplements) to make sure these won't cause further liver damage.

Anyone who has ever tested positive for hepatitis B cannot be a blood donor.

Can Hepatitis B Be Prevented?

Yes. Newborn babies in the United States now routinely get the hepatitis B vaccine as a series of three shots over a 6-month period. There's been a big drop in the number of cases of hepatitis B over the past 25 years thanks to immunization.

Doctors also recommend "catch-up" vaccination for all kids and teens younger than 19 years old who didn't receive the vaccine as babies or didn't get all three doses. Anyone who is at risk for hepatitis B (including health care and public safety workers, people with chronic liver disease, people who inject drugs, and others) also should be vaccinated.

If someone who hasn't been vaccinated is exposed to HBV, doctors may give the vaccine and/or a shot of immune globulin containing antibodies against the virus to try to prevent the person from becoming infected. That's why it's very important to see a doctor immediately after any possible exposure to the virus.

To prevent transmission of hepatitis B through infected blood and other body fluids, adults and teens should: